BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
The Bonneville Shop JRC Engineering dealers
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
Mike Austin
Mike Austin
Murrieta California
Posts: 26
Joined: September 2017
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
41 registered members (Alan_nc), 278 guests, and 392 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Tim Pedder, blayde54, Davenz13, Sean65, Rerock
10478 Registered Users
Top Posters(30 Days)
NickL 89
franko 78
Triless 69
Popular Topics(Views)
748,756 mail-order LSR
Forum Statistics
Forums34
Topics68,848
Posts670,637
Members10,478
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
And the Winner is - #758408
12/07/18 3:36 am
12/07/18 3:36 am
Joined: Jan 2004
Posts: 3,902
ca, us
D
DMadigan Offline OP
BritBike Forum member
DMadigan  Offline OP
BritBike Forum member
D

Joined: Jan 2004
Posts: 3,902
ca, us
I am not a fan of the rubber mounting of the gantry on the triples. It sags and interrupts the flow with the steps between the two spigots and rubber tube. The Japanese rubber mounts had cast couplings that filled the space between the carb and head for a smoother transition. Because of the 15 degree angle of the A75 cylinder, the spigots are cast aluminum and angled to make the carbs sit horizontal. The T150 spigots are steel and straight. The spigots are different diameters, the A75 is 1.25", the T150 is 1.162". The gantry spigot matches the intake spigot diameter so the A75 and T150 gantries are not interchangeable.
The first change was to replace the spigots at the head and gantry with a single tube making a smooth port from carb to valve. The second was to replace the 626 AMAL carbs with a larger diameter carb with a tapered transition tube. I have a couple of 930 Amals from a twin but I would need three. I looked at alternatives and decide on 30mm Oko PWK carbs. These use the same needles and jets as the Kehein PWK so tuning parts are readily available.
I made a new manifold and tubes to mount these carbs.
The AMAL carbs with tube pressed into the gantry looks like this:
[Linked Image]
The Oko PWK cabs with new manifold looks like this:
[Linked Image]
The Oko carbs are spigot mount so the manifold has an O-ring to seal the spigot and an aluminum ring with O-rings to adapt the airbox. The airbox bolts clamp the carbs into the manifold.
To compare the three arrangements I put them on the flow bench with a stock head. Measurements were taken at wide open throttle at 0.30" and 0.39" lift. The stock arrangement measured 61 CFM and 61.5 CFM. With the 626 Amals and straight tube measurements were 62 CFM and 63 CFM. The 30mm Oko carbs measured 66 CFM at both lifts.
The smooth tube added little to the stock flow but the larger carb with tapered tube added 8% increase in flow. The same flow at both lifts indicates the limit is probably from the downstream constant diameter in the head.

Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: And the Winner is - [Re: DMadigan] #758577
12/08/18 6:39 am
12/08/18 6:39 am
Joined: Sep 2001
Posts: 674
Great Southern Land
tridentt150v Offline
BritBike Forum member
tridentt150v  Offline
BritBike Forum member

Joined: Sep 2001
Posts: 674
Great Southern Land
So 8% Dave....is this across the board? or after a certain throttle opening - say 80% throttle opening. The reason I ask is because we would all want to know where we could feel/ use the extra flow [probably an impossible question]. If you are sitting on 1/4 throttle doing 60 mph and you accelerate to overtake a truck etc if its at 80% you still may not see or use that extra flow. But if it is lower down then then you may be able to use it regularly.

Nice work BTW.

Re: And the Winner is - [Re: DMadigan] #758610
12/08/18 5:19 pm
12/08/18 5:19 pm
Joined: Jan 2004
Posts: 3,902
ca, us
D
DMadigan Offline OP
BritBike Forum member
DMadigan  Offline OP
BritBike Forum member
D

Joined: Jan 2004
Posts: 3,902
ca, us
I only tested the three variants to see if there was an improvement over the stock setup. The first option, the straight tubes replacing the rubber couplings, was a solution to the T150 carb interference with the starter. The tubes were to be angled up slightly so the carb bowls would not have to be changed to the drainless type. It seemed like a clean work around.
The second option with the Oko carbs would not need the angled tubes at the head because the bowls are shorter than the Amals. Making the flanges angled to the tubes requires pressing them in on a jig to get all three correctly orientated. Then they have to be machined on the head side afterward because the tubes have to be pressed through the flanges to get a smooth bore all the way through. Otherwise there is no easy way to make the nut side of the flange parallel to the head side.
I chose slightly larger bore carbs because a tapered tube accelerates the flow and the measurements show it is better than the straight tube.
The Oko carbs use the same jets and needles as the Kehein PWK carbs so tuning parts should be readily available. Many AMAL carbs are not in the best of shape from wear and age but few will replace them because of the cost.

Re: And the Winner is - [Re: DMadigan] #758656
12/09/18 4:28 am
12/09/18 4:28 am
Joined: May 2013
Posts: 215
Fl., U.S.A.
Thunderbutt Offline
BritBike Forum member
Thunderbutt  Offline
BritBike Forum member

Joined: May 2013
Posts: 215
Fl., U.S.A.
Dave, any chance of developing a set like this for the T160? I would like to ditch my Amals .

Re: And the Winner is - [Re: DMadigan] #758683
12/09/18 4:54 pm
12/09/18 4:54 pm
Joined: Jan 2004
Posts: 3,902
ca, us
D
DMadigan Offline OP
BritBike Forum member
DMadigan  Offline OP
BritBike Forum member
D

Joined: Jan 2004
Posts: 3,902
ca, us
I would have to make runs through the full range of throttle opening to make a comparison. There probably is not a great deal of improvement at small opening since there is a lot of turbulence generated by the slide.
I do not have a T160 to see what differences there are. I presume the head mounting is the same? Does the airbox attach by two bolts between the carbs like the R3/T150? The Oko intake is larger in diameter than the AMAL. I added a ring to seal the end of the carb and provide a flange for the airbox to mount against
Clive Scarfe made a special stainless airbox (perforated R3/T150 style) with the holes to match these carbs. I will be stocking a few over here but they can be ordered direct.

Re: And the Winner is - [Re: DMadigan] #758758
12/10/18 6:01 am
12/10/18 6:01 am
Joined: Oct 2008
Posts: 5,286
Gnashville
DavidP Offline

BritBike Forum member
DavidP  Offline

BritBike Forum member

Joined: Oct 2008
Posts: 5,286
Gnashville
Excellent!
So, how difficult would it be to adapt something like a BMW K75 fuel injection?


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: And the Winner is - [Re: DMadigan] #758761
12/10/18 6:53 am
12/10/18 6:53 am
Joined: Jan 2004
Posts: 3,902
ca, us
D
DMadigan Offline OP
BritBike Forum member
DMadigan  Offline OP
BritBike Forum member
D

Joined: Jan 2004
Posts: 3,902
ca, us
I have no experience with K75 FI but adapting throttle bodies is not a problem. I have put SV1000 throttle bodies on my Lotus Europa and SV650 throttle bodies on my Rickman-Triumph 8 valve twin. Driving them takes a specially programmed micro-controller. At the minimum it takes RPM and throttle position but it really needs air temperature and airbox pressure as well. Engine temperature is needed for cold start enrichment and fast idle warm-up.
Tuning is simpler and cheaper than with carbs since you only need to connect it to a PC and change the maps but few people would want to go this route because it does not look stock.

Re: And the Winner is - [Re: DMadigan] #758777
12/10/18 1:27 pm
12/10/18 1:27 pm
Joined: Oct 2012
Posts: 4,182
Running from demons in WNY
Hillbilly bike Online content
BritBike Forum member
Hillbilly bike  Online Content
BritBike Forum member

Joined: Oct 2012
Posts: 4,182
Running from demons in WNY
Originally Posted by DMadigan
I have no experience with K75 FI but adapting throttle bodies is not a problem. I have put SV1000 throttle bodies on my Lotus Europa and SV650 throttle bodies on my Rickman-Triumph 8 valve twin. Driving them takes a specially programmed micro-controller. At the minimum it takes RPM and throttle position but it really needs air temperature and airbox pressure as well. Engine temperature is needed for cold start enrichment and fast idle warm-up.
Tuning is simpler and cheaper than with carbs since you only need to connect it to a PC and change the maps but few people would want to go this route because it does not look stock.


Tuning injection is not necessarily easier than carbs for a street...Electronic injection has many variables and unless you know the actual values from experience it can take quite a bit of time on a dyno and road testing..Carbs are self correcting to a certain extent and have generally only three adjustable circuits..
In certain automotive drag racing classes, carbs make more power than injection simply because of the the time needed to tune the injection.
But on a street bike with no concerns for emissions,I believe a clever guy with time on his hands can work out a system using off the shelf parts and processor from Micro Squirt or similar aftermarket...A simple speed density street system needs rpm, load( vacuum), ambient and engine temp, throttle position and possibly road speed inputs..And a fuel pump,( might require a larger charging system) hoses, a bunch of wiring and mounting the sensors that many vintage bike guys dislike...I think the advantages could be worth the trouble if cost is within reason


I take off bike parts until it doesn't function, then put on just enough so it functions
Re: And the Winner is - [Re: DMadigan] #758852
12/11/18 1:35 am
12/11/18 1:35 am
Joined: Sep 2001
Posts: 674
Great Southern Land
tridentt150v Offline
BritBike Forum member
tridentt150v  Offline
BritBike Forum member

Joined: Sep 2001
Posts: 674
Great Southern Land
You won't really get much advantage over carbies vs injection on a road going bike unless you add flat topped pistons and a 4 valve head and direct injection. Some, but not enough to justify the work needed IMO.

Re: And the Winner is - [Re: DMadigan] #758877
12/11/18 4:09 am
12/11/18 4:09 am
Joined: Jan 2004
Posts: 3,902
ca, us
D
DMadigan Offline OP
BritBike Forum member
DMadigan  Offline OP
BritBike Forum member
D

Joined: Jan 2004
Posts: 3,902
ca, us
FI would not come close to the cost of the OKO triple carb. You might find used K75 throttle bodies but they will still cost more than new Okos.

Re: And the Winner is - [Re: tridentt150v] #758893
12/11/18 12:41 pm
12/11/18 12:41 pm
Joined: Oct 2012
Posts: 4,182
Running from demons in WNY
Hillbilly bike Online content
BritBike Forum member
Hillbilly bike  Online Content
BritBike Forum member

Joined: Oct 2012
Posts: 4,182
Running from demons in WNY
Originally Posted by tridentt150v
You won't really get much advantage over carbies vs injection on a road going bike unless you add flat topped pistons and a 4 valve head and direct injection. Some, but not enough to justify the work needed IMO.


Carb basic function relies on airflow and has some limitations because of that...Electronic injection does not have the same limitations...On a modified engine this can be an advantage at lower speeds ....I don't believe you need a modern engine design to take advantage of injection as evidence the many old OHV V-8's fitted with EFI. With required emission controls,newer injected OHV Harleys and Guzzis run nicely...But for the typical vintage Brit Bike, I don't think injection offers an advantage other than bragging rights


I take off bike parts until it doesn't function, then put on just enough so it functions
Re: And the Winner is - [Re: DMadigan] #758932
12/11/18 5:38 pm
12/11/18 5:38 pm
Joined: Dec 2013
Posts: 4,577
ohio, usa
kevin roberts Offline

DOPE
kevin roberts  Offline

DOPE

Joined: Dec 2013
Posts: 4,577
ohio, usa
i think the fact that the fastest old brit bikes currently use magnetos and carburetors is something to think about. that may change over time.

i suspect that the precision tuning offered by injection would be wasted on a machine that is limited in other ways.


"Are bikes so nice as all that?" asked the mole, shyly...

"Nice? They're the only thing," said the Water Rat Solemnly, as he leaned forward on the handlebars. "Believe me, my young friend, there is nothing -- absolutely nothing -- half so much worth doing as simply messing about with bikes."
Re: And the Winner is - [Re: Hillbilly bike] #758996
Yesterday at 03:26 AM
Yesterday at 03:26 AM
Joined: Sep 2001
Posts: 674
Great Southern Land
tridentt150v Offline
BritBike Forum member
tridentt150v  Offline
BritBike Forum member

Joined: Sep 2001
Posts: 674
Great Southern Land
Originally Posted by Hillbilly bike
[quote=tridentt150vI don't believe you need a modern engine design to take advantage of injection as evidence the many old OHV V-8's fitted with EFI.

I have limited knowledge of these 'old V8s' but afaik they are throttle body injection [similar to what our bikes would have to go with]. Direct injection came much later. This method was inherently inefficient...dinosaur with a band aid! It was only done in desperation in a declining market and surging fuel prices. I would be amazed if there was any massive benefit from this. I think it was also a knee jeeerk mod to show that the American car industry [and the Australian/English one as well] - so lets say traditional - could match it with the modern offerings from Japan and Europe. It was always a stop gap until they caught up.
This was similar to the V8's that could switch to a 4 cylinder in cruise mode and the petrol motor V8's that had a diesel head slapped on them in cars like the Cadillac.

Again I say "You won't really get much advantage over carbies vs injection on a road going bike unless you add flat topped pistons and a 4 valve head and direct injection"....but note I didn't say NO advantage, just not enough to warrant the work needed.

Inversely, I wouldn't go to the trouble of installing carbies on a throttle body/inlet tract type injected motor.....again....nil advantage.

Last edited by tridentt150v; Yesterday at 03:26 AM.
Re: And the Winner is - [Re: DMadigan] #759006
Yesterday at 06:20 AM
Yesterday at 06:20 AM
Joined: Feb 2015
Posts: 308
Melbourne Oz
S
Steven A Offline
BritBike Forum member
Steven A  Offline
BritBike Forum member
S

Joined: Feb 2015
Posts: 308
Melbourne Oz
Originally Posted by DMadigan
I have no experience with K75 FI but adapting throttle bodies is not a problem. I have put SV1000 throttle bodies on my Lotus Europa and SV650 throttle bodies on my Rickman-Triumph 8 valve twin. Driving them takes a specially programmed micro-controller. At the minimum it takes RPM and throttle position but it really needs air temperature and airbox pressure as well. Engine temperature is needed for cold start enrichment and fast idle warm-up.
Tuning is simpler and cheaper than with carbs since you only need to connect it to a PC and change the maps but few people would want to go this route because it does not look stock.



I do! Microsquirt?

Last edited by Steven A; Yesterday at 06:20 AM.


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.2